Think it’s inside the cage where you’re most at risk? Well as soon as you step out of it, there’s a whole host of viruses ready to take you down.

It’s time to fight back...

After finishing another epic training session you’re covered in blood, sweat and spit. It’s a sign that you’ve pushed yourself to the limit.

Your work is done. You feel charged up and invincible as you take off your gloves and walk out the gym. But the truth is, you’re now a walking target.

Known as the ‘open window’ theory, your immune system is seriously reduced immediately after intense exercise, meaning all these bodily fluids will harbor hidden bacteria and viruses that want to take you down and tap you out. The theory, also known as the acute immune response, posits that after heavy training sessions you’re open to upper respiratory tract infections (URTIs) – or colds and flu in layman’s terms.

Professor David C Nieman is an exercise immunology specialist and author of the study Effects of Exercise on the Immune System which appeared in the publication Immunology and Cell Biology.

Dr Nieman’s not just an academic – he’s run 58 marathons and ultramarathons and was an acrobatic gymnast and coach for 10 years.

In his paper he states: “Many components of the immune system exhibit adverse change after prolonged, heavy exertion,” and goes on to add that “although still open to interpretation, most exercise immunologists believe that during this ‘open window’ of impaired immunity (which may last between three and 72 hours, depending on the immune measure) viruses and bacteria may gain a foothold, increasing the risk of infection.”

This has serious implications for fighters in the gym.

Nobody wants to lose valuable training time or infect their training partners because they’ve got a bad cold.

It’s for this reason that Alex Ariza, strength and conditioning coach to boxers Manny Pacquiao and Amir Khan, dislikes the ‘Pac-Man’s habit of shaking hands with his adoring public immediately after open workout sessions. As he has says: “His immune system is compromised,” and, “there are lots of germs around.”

Dr Happy Reynolds is a mixed martial arts ringside physician for the California State Athletic Commission and a former competitive Muay Thai boxer. She explains how the open-window theory works.

Cautioning against paranoia, she stresses that, “the theory is based on the physiology of heavy endurance training.” This is in reference to the fact that studies have been carried out on marathon runners and triathletes, but not on fighters.

But if your training sessions are intense, three-hour plus affairs (which we hope they are), read on...

Dr Reynolds says: “Your body produces more of the hormone cortisol under stress, both physical and emotional. The cortisol in turn decreases the cilia [finger-like cells that sweep up mucus and dirt] in your nose and upper respiratory tract, meaning that you would be more susceptible to colds and other URTIs. It also seems to make the white blood cells that are the first responders to infection less sensitive.”

She again reminds us that this is not a problem if all you’ve done is five rounds on the heavy bag and adds: “This change is not seen in moderate exercise – only very heavy competitive training.”

Cutting through the technicalities, she gets straight to the point, finally stating: “So what the hell does any of that mean to real people?

It means if you are sick, stay the f**k out of the gym!”

Avoid the germs in the gym with these top tips for preventing infection during the open window…

> KEEP IT CLEAN

Shower immediately after training. Don’t forget to wear flip-flops: the floors of public showers are notorious for collecting germs and it just takes one cut or scratch on your foot for infection to take hold.

When in the changing room, put a towel on the bench before you sit on it (imagine how many sweaty rears have stained that over time).

Avoid putting your hands to your eyes and nose unless you have just washed. This is the number one way of germs being transferred – very few are transmitted through the air.

Keep your gym kit clean and use sanitizer on your gloves and pads.

Don’t share water bottles or drink from the gym water fountain.

> DEFEND YOURSELF AT ALL TIMES

Don’t lower your guard on the way home: avoid crowded public transport if possible.

If you have to take the bus, carry hand sanitizer and use it.

Wash your hands when you get home. The effect of sanitizers is limited: hot water and soap plus a good 10-minute scrub will do the job properly.

Avoid sick people and crowds if possible: stay away from press conferences, doctors’ waiting rooms, schools and similar group situations.

> COME OUT FIGHTING

Good general health is your best protection. Keep stress to a minimum (Dr Nieman points out that “mental stress in and of itself has been linked to increased URTI risk”).

Avoid rapid weight-cutting, which can put pressure on the immune system.

Stay hydrated. Keeps your eyes and nose moist to repel parasites.

Get a flu vaccination if training in winter.

FEEDING OFF INFECTION

While plenty of supplements are marketed as immune-system boosters, there’s still no hard evidence to suggest that they help during the window. Dr Neiman says: “Vitamin and glutamine supplements have received much attention, but the data thus far do not support their use as countermeasures to exercise-induced alterations in immunity.

At this point, athletes should eat a varied and balanced diet.” 

He does, however, recommend carbohydrate supplementation before, during and after intensive endurance exercise lasting longer than 90 minutes. Carbohydrate beverages – i.e. energy drinks – can help keep blood glucose levels higher, reduce the production of cortisol, reduce fluctuations in blood immune cell counts and have other physiologically beneficial effects.